For as much as she laughs, it’s hard to take Camille Herron seriously. Her record of 14 marathon wins in 28 starts—one while wearing a Spiderwoman costume—shows otherwise though, and she insists that she’ll be at her best at Sunday’s Comrades Marathon in South Africa.

Comrades is no marathon distance, though. It is actually 89K, with a 56-mile point-to-point course from inland Pietermaritzburg to coastal Durban in the country’s Kwazulu-Natal Province. It will be the longest Herron has ever run, but with a marathon best of 2:37, she says she has the leg speed to do well on this year’s downhill route (the course reverses directions from year to year).

“Being in contention to win would be a dream come true,” the chatty 32-year-old from Oklahoma says. “Top five or top ten would be great.”

Sunday’s race may reveal Herron as one of America’s best ultramarathoners, but she’s actually never raced an ultramarathon stateside. She expects to eventually dip her toe into USA Track & Field ultra road championships. “I’m definitely a road racer. It’s where I’m most comfortable. Comrades is a first test to see what I think of it, what I need to work on,” she says.

Comrades is the most competitive ultramarathon in the world. Its 18,000 entrants come from up to 60 different countries. Russian twins Elena and Olesya Nurgalieva have had a stranglehold on the race for more than a decade, winning 10 times since 2003. Elena has won four straight times. They finished first and second last year, 16 minutes ahead of third place.

Herron’s marathon wins have been at second-tier races, in terms of competition, and it was just a year ago that she made her ultra debut. In March 2013 at South Africa’s Two Oceans Marathon she finished 11th, but was later bumped to 10th when the first-place finisher failed a drug test. Although Herron was inside the top-10, she was also 13 minutes slower than the eventual race winner. It was a disappointing race and she chocked it up to ultra inexperience. She simply settled into a dawdling pace early on and the race passed her by.

“I went out way too relaxed. It was slow and uncomfortable. I like to go out conservatively and finish strong, but it was depressing. I didn’t feel like I was in the race,” she says of her debut performance. “Less than five times in my running career have I cried, and that was one of them.”

This year she’s feels fitter than ever and pledges to run her own race while being competitive. She hasn’t tailored her training to Comrades, but instead heeded the words of her Nedbank team manager, Nick Bester, a South African who won the race’s 1991 edition.

“I trained like a marathoner, fresh and fast,” Herron says. She ran five marathons in 10 weeks to start the year, not peaking for any and hitting a seasonal best of 2:42. Although she’s never run farther than the 56K completed at last year’s Two Oceans race, she’s averaged 100-plus miles per week since late 2006. Having recently returned to full-time work, she’s now dropped from 120-140 miles per week to 100-120. A pair of lungs on long legs, Herron is aerobically fit and confident that her consistency will be sufficient for the longer race distance.

Born and raised in Oklahoma, and now living in suburban Oklahoma City, Herron knows that the state’s runners don’t hold the same cachet as those from Flagstaff or Boulder, and Oklahoman ultrarunners at the highest level are few to none. When travelling to bigger races, “I’m the first person from Oklahoma most runners have met,” she jokes. That’s likely to be especially true at a race as exotic as Comrades.

On Sunday, at the 89th running of the Comrades Marathon in South Africa, she gets her shot at the world’s best.